1. Field of the Invention
The invention relates to a method of and a strand guide for supporting, guiding and cooling of cast strand made of steel, in particular, beam-blank preliminary sections for girders, wherein the cast strand, after leaving a continuous casting mold, is cooled by a secondary cooling in a nil segment and is further cooled in the following support segments by spray water and is drawn out.
2. Description of the Prior Art
JP 42 00 844 discloses providing, in a strand guide, separate support rollers for longitudinal sides of the cast strand cross-section, in form of “jog” rollers and long rollers having a reduced length and arranged in the profile base. On the cast strand side, support rollers having a corresponding length are arranged. This arrangement does not take into account the strand shell thicknesses associated with the points on cast strand and the necessary cooling.
It is to be noted that the functions of the strand guide include not only providing a support for the cast strand against the ferrostatic pressure but also removal of the heat of solidification by secondary cooling and retaining of the profile geometry produced in a continuous casting mold. However, always, surface cracks are formed.
The object of the strand guidance should be obtaining of error-free surface quality of a cast strand, inner quality without cracks and segregations, with maintaining of exact profile.
The object of the invention is to prevent cracks in the microstructure, in particular cracks caused by cooling, by adapting cooling conditions of the strand surface to the secondary cooling, in particular, by preventing undercooling.